This invention relates to surgical suturing instruments. More particularly, it relates to instruments having jaws for successively clamping and suturing a portion of body tissue in an essentially unitary manipulative operation, wherein the suture to be applied is carried in one of the jaws and passed therefrom through the tissue while the jaws are clamped.
In a specific sense, the invention is directed to improvements in suturing instruments of the general type specifically exemplified by illustrative embodiments described in U.S. Pat. No. 3,807,407. That patent discloses a suturing instrument comprising a pair of pivotally interconnected jaws, one of which carries a flexible suture with a pair of needles attached to the suture ends, and contains a plunger for transferring the needles to the second jaw through a portion of body tissue clamped between the jaws. The second jaw has a pair of apertures for receiving and frictionally retaining the needles and is provided with a handle. An actuator arm, mounted on the same pivot as the two jaws, is connected to the plunger; and means are provided for selectively interconnecting the first jaw with the actuator arm and with the second jaw in succession during progressive closing movement of the actuator arm and the handle of the second jaw. The actuator arm and the second-jaw handle are disposed to be grasped by the thumb and fingers of the user's hand and to be manipulated in forceps-type opening and closing action.
In the use of this instrument, in the initial stage of closing movement of the arm and handle, the arm (being maintained in fixed relation to the first jaw by the interconnecting means) swings the first jaw into a closed or clamping position relative to the second jaw. At that point, the first jaw becomes disconnected from the actuator arm and interlocks with the second jaw so as to be held in fixed relation to the second jaw during further closing movement of the arm. Since the arm is now no longer fixed in relation to the first jaw, such further closing movement of the arm advances the plunger within the first jaw, forcing the needles through a portion of tissue clamped between the jaws and into the needle-receiving apertures of the second jaw. Upon re-opening of the instrument, the needles (being retained in the second jaw) draw the suture through the tissue; the needles may then be clipped off and removed, and the free ends of the suture may be tied.
An advantage of the described instrument is that the clamping pressure exerted on the tissue between the jaws is limited by the interlocking of the jaws; thus, the plunger-operating movement of the actuator arm (after the tissue has been initially clamped) cannot cause excessive compression of the clamped tissue. Also, the plunger cannot be operated until the actuator arm is disconnected from the first jaw, as is desired to prevent discharge of the needles from the first jaw until the second jaw is positioned to receive them. The structures heretofore proposed for use as the interconnecting means of such an instrument, however, have relied on spring forces to maintain the interconnection at least between the first jaw and the actuator arm. The spring or springs employed to exert these forces are subject to failure through fatigue; moreover, if the tissue to be clamped and sutured is tough or resistant to compression, the spring forces may yield prematurely and the actuator arm may then move the plunger to discharge the needles while the jaws are still partially open, with the result that the suture is not applied because the needles do not enter the receiving apertures of the second jaw. In such case, difficulty and inconvenience as well as loss of valuable time may attend the location and removal of the discharged needles.
In addition, in arrangements heretofore proposed for the needle-receiving apertures, the needles are withdrawn from the apertures through the same openings they enter when transferred from the first jaw. In some instances, upon opening of the instrument after the needles have been transferred, passage of the suture through the tissue may be sufficiently hindered or retarded to cause premature withdrawal of the needles from the apertures, again occasioning inconvenience and difficulty.
In one embodiment of the instrument described in the above-cited patent, the suture, together with its needles, is contained in a capsule removably mounted in the first jaw so that after the suture is used, the empty capsule may simply be discarded and replaced with a fresh suture-containing capsule, i.e. enabling immediate application of a second suture. Within the capsule, the central portion of the suture is wound on a bobbin, while the needles (attached to the suture ends) are positioned for engagement with the plunger and for discharge by the plunger through the clamped tissue and into the second-jaw apertures. For proper suturing action, it is important that the two ends of the suture be withdrawn at the same rate from the capsule as the instrument is re-opened; however, in embodiments of the bobbin heretofore proposed, it has been possible for the suture to be nonuniformly wound, i.e. so that the two ends are not paid out evenly. Such uneven discharge of the two suture ends hinders proper functioning of the instrument.
Another form of the instrument described in the above-cited patent is adapted to apply staples rather than flexible sutures (e.g. filaments or threads). These staples are contained in a magazine or capsule in the first jaw and are forced through a clamped portion of body tissue by the plunger, being bent by a facing surface of the second jaw so as to grip the tissue. As used herein, the term "suture" embraces such staples as well as flexible sutures.